There are many constructions of flexible bags made of plastic material and provided with some type of pressure sensitive adhesive closure strip, making the same easy and convenient to close. Some designs incorporate a removable liner applied over the closure strip prior to use. Use of such a liner represents undesirable expense compared to the cost of the material of the bag itself. U.S. Pat. Nos. 2,671,602, issued to Vogt; 2,715,493, issued to Vogt; 3,915,302, issued to Farrelly et al.; and 4,502,599, issued to Perecman all represent attempts to eliminate the need for a disposable liner by releasably adhering multiple bags sequentially together with exposed adhesive strips. A bag may be detached from the stack with the adhesive strip exposed for use in sealing the bag. However, such arrangements are not applicable to singly provided bags.
U.S. Pat. Nos. 3,942,713, issued to Olson et al.; 3,990,627, issued to Olson; and 4,581,007, issued to Kamp all relate to designs incorporating a "Z folded flap" in either the front or the rear panels of the bag to cover a closure strip of pressure sensitive adhesive prior to use. These types of arrangements, although useful, involve complicated and relatively expensive manufacturing operations in aligning the strip of pressure sensitive adhesive with the Z folded flap.
U.S. Pat. No. 3,420,433, issued to Bostwick discloses a bag with a closure strip of pressure sensitive adhesive on a front surface of the back panel of the bag. A portion of the back panel above the closure strip is folded over to cover the closure strip prior to use. This arrangement also requires additional manufacturing steps to align the folded over flap with the closure strip and to fold over the flap.